There is a current emphasis on increasing the uses of recycled materials, specifically polymeric resins. As one example, poly(ethylene terephthalate) (PET) is one of the major post-consumer plastic wastes within the U.S. and around the world. According to the National Association for PET Container Resources (NAPCOR), over 771 million lbs. of post-consumer PET were recycled and sold or exported from the U.S. in 1999. However, this is believed to be only 24 percent of the total amount of PET available for recycling. While some of the challenge to increase recycling lies in the ability to collect the post-consumer products, the viability of the recycling industry, in all likelihood, ultimately depends on producing high-value products from post-consumer waste. This capability most likely does not exist at present with PET. For example, in 1999, it was estimated that 59 percent of the recycled post-consumer PET was used as fiber in applications such as sleeping bags, bedding and clothes. It is further estimated that only 9 percent was suitable for bottle-to-bottle recycling, the highest value-added product.
There are three main types of post-consumer recycling: reuse, physical reprocessing, and chemical reprocessing. Reuse of polymeric packaging materials, common for glass, is largely not acceptable for most of the currently collected, post-consumer PET. Physical reprocessing typically involves grinding, melting and reforming of the plastic packaging. During physical processing, the basic polymer molecules are typically not altered. Moreover, it may be extremely difficult, if not impossible, to remove contaminants to very low levels using physical processing. Finally, chemical reprocessing involves depolymerization of the used packaging material with subsequent regeneration and purification of the resulting monomers (or oligomers). The monomers are then repolymerized and new packaging is formed.
The Food & Drug Administration (FDA) has issued letters of “no objection” for direct food contact for several depolymerization processes. In one embodiment of an FDA-approved process, solid particles of PET are contacted with a depolymerization agent such as, for example, methanol or ethylene glycol and the starting monomers of ethylene glycol (EG) and dimethyl terephthalate (DMT) are typically recovered. It should be appreciated that other depolymerization agents can be used with other various polymers as set forth herein in greater detail. Methanolysis and glycolysis reactions are shown in Scheme 1. 
One of the main disadvantages associated with conventional depolymerization processes is that several purification steps are typically needed to obtain usable monomers. In addition to chemical depolymerization, contaminants associated with the polymers need to be removed from the monomers to very low levels. This often requires several purification steps, including washing, distillation, crystallization and additional chemical reactions. The cost of these additional cleaning steps usually dramatically increases the effective cost of the recycled monomers. In addition, long reaction times are typically required for depolymerization processes.
In order to sustain and expand the recycling industry, there is a need in the art to provide new recycling approaches that are capable of increasing the ability to recycle post-consumer step-growth polymers (e.g., PET) into bottles, other food packaging materials, or other high value-added products in a more efficient manner.